Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
  • H04B1/0007—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage
  • H04B1/001—Channel filtering, i.e. selecting a frequency channel within the SDR system
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/06—Receivers
  • H04B1/16—Circuits
  • H04B1/26—Circuits for superheterodyne receivers
  • H04B1/28—Circuits for superheterodyne receivers the receiver comprising at least one semiconductor device having three or more electrodes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/40—Circuits
  • H04B1/401—Circuits for selecting or indicating operating mode
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
  • H04B1/40—Circuits
  • H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
  • H04B1/406—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency with more than one transmission mode, e.g. analog and digital modes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/24—Reselection being triggered by specific parameters
  • H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
  • H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/14—Reselecting a network or an air interface
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/02—Terminal devices
  • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Definitions

• the invention relates generally to communication systems and, more particularly, to inter radio access technology (RAT) operation in at least one communication system.
• RAT radio access technology
• Super 3G Orthogonal Frequency Division Multiplexing
• S3G One proposal, referred to as Super 3G or S3G, can be seen as an evolution of the 3G WCDMA standard.
• Super 3G will likely use OFDM as a modulation technique, and will operate on a bandwidth that spans from 1.25 MHz to 20 MHz, with data rates up to 100 megabits per second (Mb/s) possible. Therefore, for smooth migration, within the existing radio spectrum, of the "old" cellular systems to the new high-capacity, high-data rate cellular systems, user equipment will need to be capable of operation on a flexible bandwidth.
• inter RAT operations involve adapting the receiver to the bandwidth and HO/cell search parameters of a certain cellular system, performing the cell search, measurements, etc., using the access technology of that cellular system, then adapting the receiver to a different access technology of another cellular system, and performing the cell search, measurements, etc., using that different access technology.
• an ongoing communication session such as a speech or data call, supported by a first access technology
• the ongoing communication session is interrupted in order to permit cell search/measurements on the second access technology.
• Interruptions in ongoing communication sessions can be avoided if the terminal is provided with multiple receiver branches, including multiple antennas, multiple front end receivers, etc. This permits the ongoing communication session to continue on one receiver, adapted to a first access technology, while cell search/measurements are simultaneously performed using the other receiver, adapted to a second access technology. This two-receiver approach is expensive from the terminal perspective.
• the present invention is an apparatus and method adapted to facilitate inter RAT operation in at least one communication system.
• the apparatus of the present invention includes an adjustable front-end receiver having an adjustable AF coupled to the front end receiver.
• an ADC coupled to the AF and a plurality of extraction units adapted to receive digital signals from the ADC.
• Coupled to the plurality of extraction units is a plurality of evaluation units and a plurality of detection units with a first control unit controlling a switching arrangement and fixing the frequency and bandwidths of at least one of the plurality of the extraction units based on signals received from at least one of the plurality of the evaluation units and detection units.
• the method of the present invention includes receiving frequency signaling throughout a first frequency bandwidth that includes a first carrier frequency and then converting the analog signal produced in the receiving step into a first digital signal that corresponds to the first frequency bandwidth.
• a further step is extracting from the first digital signal a secondary digital signal that is within a secondary frequency bandwidth which is equal to or within the first frequency bandwidth and which includes a secondary carrier frequency, the secondary frequency bandwidth and the secondary carrier frequency associated with communication in a first of a plurality of communication systems.
• a further step is extracting from the first digital signal at least one additional secondary digital signal that corresponds to a frequency bandwidth which is also equal to or within the first frequency bandwidth and which also includes a carrier frequency, the at least one additional secondary frequency bandwidth and its corresponding carrier frequency being associated with communication in a communication system similar to or different from that used the secondary digital signal.
• Figure 1A diagrammatically illustrates a terminal apparatus according to embodiments of the invention
• Figure 1B diagrammatically illustrates another aspect of the terminal apparatus of Figure 1A
• Figure 2 graphically illustrates an example of relative portions of the frequency spectrum that can be accessed by embodiments of the invention
• Figure 3A diagrammaticalfy illustrates a terminal apparatus according to further embodiments of the invention.
• Figure 3B diagrammatically illustrates a simplified version of the terminal apparatus of Figure 3A;
• Figure 4 diagrammatically illustrates a terminal apparatus according to further embodiments of the invention.
• Figure 5A is a flow chart illustrating a set of operations performed according to the invention.
• Figure 5B is a flow chart illustrating a method of the present invention.
• Figure 6 diagrammatically illustrates a terminal apparatus according to further embodiments of the invention.
• Embodiments of the invention provide a terminal with a front end receiver operable throughout a bandwidth that is large enough to cover the entire bandwidth used by access technologies supported by the terminal.
• the front end receiver would be operable across the entire 20 MHz bandwidth used by an OFDM signal, and could therefore receive a bandwidth that is larger than that of GSM (200 kHz) and WCDMA (5 MHz).
• GSM 200 kHz
• WCDMA 5 MHz
• FIG. 1A diagrammatically illustrates a terminal apparatus 1 according to embodiments of the invention.
• a front end receiver (RX) 2A is capable of receiving a signal with bandwidth BWo (e.g., 20 MHz) which can be tuned to a first carrier frequency f 0 and filtered via analog filter (AF) 2B.
• BWo bandwidth
• AF analog filter
• the frequencies in the interval fo +/- BWo/2 can be differentiated from unwanted signals by the front end receiver 2A and AF 2B.
• the desired carrier frequency and bandwidth e.g., fo and BWo
• are adjustable and can be specified at inputs 3A and 3B.
• the terminal of Figure 1A is capable of communicating with a communication system A (not explicitly shown) using a carrier frequency fA and bandwidth BW A , both of which are included in the aforementioned operating bandwidth of the front end receiver 2A and AF 2B, as shown in Figure 2.
• the example of Figure 2 is provided for general illustrative purposes only, and is not necessarily drawn to scale.
• the input signal at carrier frequency fo and having bandwidth BW 0 , is down-converted to an analog baseband signal, which is then converted from analog to digital format by an analog-to-digital converter (ADC) 4.
• ADC analog-to-digital converter
• the resulting digital signal is fed to units adapted to extract signals, extraction units 5 and 6.
• the extraction unit 5 uses the frequency f A to down- convert the digital signal to a digital baseband signal, and also implements a low-pass filter of bandwidth BW A .
• the use of these types of digital processing operations to extract a desired frequency carrier and bandwidth are well known in the art.
• the signal extracted by extraction unit 5 is routed by a switching arrangement 7 controlled by a control unit 10 to one of a plurality of ATI-ATm detection units 8 that is adapted to the access technology used by the communication system A.
• ATI-ATm detection units 8 that is adapted to the access technology used by the communication system A.
• AT1 access technology
• ATm access technology
• each of the illustrated detection units 8 is capable of performing signal detection according to techniques that are well known in the art.
• Figure 1B diagrammatically illustrates in more detail the aforementioned ATI-ATm detection units 8 of Figure 1A.
• Figure 1B shows a set of detection units for S3G and WCDMA signals. Note that the present invention encompasses any number of detection units optimized for any type of signal.
• the signal detected by the selected detection unit 8 is provided to first control unit 10, which forwards information contained in the detected signal for further processing at 11 as seen in Figures 1A and 1B.
• the first control unit 10 also has a control output designated generally at 12, which is used to provide control information for the extraction units 5 and 6 and path selection information to control the operation of switching arrangement 7.
• the control output 12 is further detailed as control output 12A, which is used to provide control information, such as the carrier frequency f A and bandwidth BW A for the extraction unit 5, and control output 12B, which is used to provide control information, such as carrier frequency f ⁇ and bandwidth BW B, for the extraction unit 6, and path selection information to control the operation of the switching arrangement 7.
• the first control unit 10 also uses neighbor list information (which is conventionally available in the signal produced by the selected detection unit) to learn which carrier frequencies, bandwidths and access technologies are utilized by neighboring cells.
• first control unit 10 can use the control output 12 to control extraction unit 5 and switching arrangement 7 to produce desired evaluations of neighboring cells.
• the first control unit 10 can direct the extraction unit 5 to perform generally the same operations described above with respect to extraction unit 6, but to use another carrier frequency f ⁇ and another bandwidth BW 8 (see also Figure 2).
• the first control unit 10 also directs switching arrangement 7 appropriately to route the output of extraction unit 5 to one of a plurality of ATI-ATn evaluation units 9 associated with the access technology (e.g., GSM, WCDMA, OFDM-based systems) used by the cell that is to be evaluated.
• the access technology e.g., GSM, WCDMA, OFDM-based systems
• FIG. 1B diagrammatically illustrates in more detail the aforementioned ATI-ATn evaluation units 9 of Figure 1A. As seen therein, certain operations occur depending on the type of technology access.
• detector 8A For a S3G signal, detector 8A performs channel estimation and determines its signal to interference ratio (SIR) (techniques well known in the art), filters the signal through a matched filter (MF) and then decodes the signal.
• SIR signal to interference ratio
• evaluator 9 performs cell search and determines SIR in separate modules.
• Figure 1B shows a set of evaluation units for S3G and WCDMA signals, the present invention encompasses any number of evaluation units optimized for any type of signal.
• each of the evaluation units 9 is capable of performing operations such as HO measurements and cell searches according to techniques that are well know in the art.
• the terminal can, while simultaneously supporting an ongoing communication session with the aforementioned cell A ⁇ i.e., using extraction unit 5 as described above), perform operations such as HO measurements, cell searches, etc. with respect to communication systems in neighbor cells that use access technologies which differ from the access technology used by cell A.
• the ongoing communication session with cell A need not be interrupted.
• the evaluation results from the evaluation units are provided to the first control unit 10, and can be processed therein, or forwarded at 11 for further processing. If a new cell becomes stronger than the current cell on fA, then a handover can be executed according to conventional practice. If the new cell uses an access technology that differs from the access technology of cell A, then this handover is an inter RAT handover.
• Figure 3A diagrammatically illustrates a terminal that is capable of efficiently performing cell evaluations while the terminal is in standby mode, according to embodiments of the invention.
• the terminal In standby mode, the terminal is "on", but not in use, so low power consumption is important.
• conventional terminals in standby mode will “wake up” periodically (e.g., once per second) and turn on its front end receiver to receive and read paging messages to determine if there are any messages for the terminal, and to perform cell measurement operations to determine whether there are any stronger cells on which to camp.
• the terminal of Figure 3A is similar to that of Figure 1A, but includes a digital data storage unit 31 coupled to the output of the ADC 4.
• the digital signaling output from the ADC 4 is stored in the storage unit 31.
• the first control unit 10 can use its control output 12A to effectuate the desired paging detection (e.g., detection on carrier frequency f A and bandwidth BW A ) via extraction unit 5 and the appropriate detection unit, in generaliy the same fashion as any other communication session.
• the front end receiver 2A including AF 2B
• the stored digital signal can be played back, and cell evaluation operations such as those described above can be performed for any desired combinations of carrier frequency, bandwidth and access technology within the bandwidth of the analog filter. Cell evaluations can therefore continue to be performed during standby mode, without requiring any additional use of front end receiver 2A and AF 2B, and thus without increasing the power consumed by front end receiver 2A and AF 2B.
• the first control unit 10 of Figure 3A can, during those time periods, (1) control the switching arrangement 7 such that each of the extraction units 5 and 6 is coupled to a respective one of the evaluation units 9, and (2) use both extraction units 5 and 6 to support cell evaluations. Cell evaluations can thus proceed simultaneously with one another, thereby reducing the time needed to perform the cell evaluations.
• the first control unit 10 controls the cell evaluations based on neighbor list information obtained during the paging message detection for the cell being camped on. ⁇ n some embodiments, the first control unit 10 controls the cell evaluations based on information about neighbor cells derived from historical information stored in the first control unit 10.
• Figure 3B diagrammaticalfy provides a simplified version of the terminal apparatus of Figure 3A.
• the extraction units 5 and 6 are comprised of mixers 32 and 34 and corresponding low pass filters 33 having BWB and 35 having BW A - These elements are adapted to permit tuning of f A and f B in the digital domain prior to the signals being fed via the switching arrangement to the detection units 8 and evaluation units 9.
• very strong adjacent channel interferers can effectively prevent the use of the full bandwidth of the front end receiver 2A. If there is a strong interferer close to the desired frequency or bandwidth, a considerable portion of that interferer may need to be filtered out upstream of the ADC 4 in order to avoid dynamics problems.
• Figure 4 diagrammatically illustrates a terminal that can minimize interference.
• the terminal of Figure 4 is similar to those of Figures 1A, 1B, 3A and 3B, but includes the capability of adjusting AF 2B relative to the full bandwidth BW 0 capability of front end receiver 2A.
• AF 2B is adjustable from 1.25 MHz to 20 MHz.
• a second control unit 41 receives, from an output 43 of first control unit 10, conventionally available information indicative of the signal quality of the ongoing communication session, e.g., the session on f A described above.
• this signal quality information is obtained from CQI (channel quality index) pilots in the system.
• the second control unit 41 continuously monitors the signal quality information, and provides to the front end receiver 2A and AF 2B control information 3A and 3B, respectively.
• the center frequency of the received signal is adjusted at front end receiver 2A via control information 3A and the analog selectivity filter of AF 2B is adjusted in response to the control information 3B, thereby adjusting the size of the bandwidth.
• the carrier frequency fo and bandwidth of the receiver are initially set to f A and BW A , respectively. Then, the receiver bandwidth is increased gradually, while continuing to monitor the signal quality information. This gradual increase continues until either the receiver bandwidth reaches its maximum available bandwidth, or the signal quality reaches a minimum acceptable quality threshold. In some embodiments, the threshold is a certain fraction of what the quality measure was when the bandwidth adjustment process began.
• the adjustments are performed periodically. In some embodiments, the adjustments are performed whenever the channel quality changes suddenly. In some embodiments, the adjustments are performed whenever the terminal executes a handover.
• FIG. 5A illustrates one of a plurality of possible bandwidth adjustment operations described above with respect to Figure 4.
• the receiver's bandwidth BWR X is set equal to BW A .
• the receiver bandwidth BW RX is increased at 53.
• the operations at 52 and 53 are repeated until either the receiver bandwidth BWR X reaches its maximum available bandwidth, here BW 0 , at 54, or the signal quality reaches a minimum acceptable quality threshold TH at 55.
• control information 3A directs the front end receiver 2A to adjust its carrier frequency fo, in order to permit use of the receiver's entire bandwidth capability, even in the presence of strong interference.
• this carrier frequency adjustment has the effect of shifting the bandwidth BW 0 relative to carrier frequency f A .
• the bandwidth BWo can be shifted enough to remove the problem interference with respect to carrier frequency f A .
• FIG. 5B is a flow chart illustrating a method of operating in a plurality of communication systems.
• a frequency signaling is received throughout a first frequency bandwidth that includes a first carrier frequency.
• an analog signal produced in the receiving step is converted into a first digital signal that corresponds to the first frequency bandwidth.
• a secondary digital signal that is within a secondary frequency bandwidth is extracted from the first digital signal which is equal to or within the first frequency bandwidth and which includes a secondary carrier frequency.
• the secondary frequency bandwidth and the secondary carrier frequency are associated with communication in a first of a plurality of communication systems.
• step 504 at least one additional secondary digital signal that corresponds to a frequency bandwidth which is also equal to or within the first frequency bandwidth and which also includes a carrier frequency, is extracted from the first digital signal.
• the at least one additional secondary frequency bandwidth and its corresponding carrier frequency are associated with communication in a communication system similar to or different from that used the secondary digital signal.
• the aforementioned method can further include storing the first digital signal so that the steps of extracting the secondary digital signal and the at least one additional secondary digital signal from the stored first digital signal occur after completion of the receiving step.
• the receiving step can further include adjusting one of the first bandwidth and the first carrier frequency based on communication quality associated with one of the secondary carrier frequencies.
• the receiving step can include adjusting the first bandwidth or the first carrier frequency based on communication quality associated with one of the secondary carrier frequencies.
• the method illustrated in Figure 5B can include performing the adjusting step at points in time that occur periodically or whenever a handover occurs.
• Figure 6 diagrammatically illustrates a terminal according to further embodiments of the invention.
• the terminal of Figure 6 is similar to those of Figures 1A, 1B, 3A, 3B and 4, but includes both the digital storage/playback capability described above with respect to Figure 3A, and the front end receiver adjustment capability described above with respect to Figure 4.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
• Container Filling Or Packaging Operations (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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Publications (1)

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• 2006
  • 2006-04-06 US US11/278,878 patent/US7680215B2/en active Active
• 2007
  • 2007-03-23 TW TW096110207A patent/TWI420864B/zh not_active IP Right Cessation
  • 2007-03-27 KR KR1020087027136A patent/KR101308166B1/ko not_active Expired - Fee Related
  • 2007-03-27 AT AT07723617T patent/ATE453963T1/de not_active IP Right Cessation
  • 2007-03-27 WO PCT/EP2007/002671 patent/WO2007112880A1/en active Application Filing
  • 2007-03-27 EP EP07723617A patent/EP2002552B1/en active Active
  • 2007-03-27 MX MX2008011532A patent/MX2008011532A/es active IP Right Grant
  • 2007-03-27 ES ES07723617T patent/ES2339068T3/es active Active
  • 2007-03-27 CN CN2007800124411A patent/CN101416404B/zh active Active
  • 2007-03-27 DE DE602007004090T patent/DE602007004090D1/de active Active
  • 2007-03-27 JP JP2009503456A patent/JP4950278B2/ja active Active
  • 2007-03-27 PT PT07723617T patent/PT2002552E/pt unknown
• 2010
  • 2010-01-27 US US12/694,740 patent/US20100128825A1/en not_active Abandoned

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